1. Field of the Invention
The present invention relates to a TAB leader tape comprising a polyphenylene ether-based resin excellent in resistance to water absorption.
2. Description of the Related Art
A printed tape having many semiconductor devices automatically mounted thereon, namely, a tape for tape automated bonding (hereinafter referred to as TAB), is wound around a reel in a form carried on a spacer tape for protecting the tape. A TAB leader tape used in mounting semiconductor drivers is connected to TAB tapes, in the winding start and winding end.
The TAB leader tape is required to have heat resistance to exhibit no deformation even under heating in an oven in the process of curing a sealing agent for semiconductor devices mounted on TAB; thus, a super engineering plastic such as polyimide, polyether imide, and polyethylene naphthalate is used as a material thereof. Specifically, a polyimide film is used for applications in which the lead tape is employed at a temperature of 180° C. or lower; polyether imide is employed for applications in which the lead tape is employed at a temperature of 160° C. or lower.
The TAB leader tape has been poorly discussed for necessary performances thereof other than heat resistance perhaps because it is used only in a small amount on the winding start and winding end of a TAB tape; it has probably been thought that the mounting can just have to be carried out at an acceptable cost. For example, Japanese Patent Laid-Open No. 2002-29939 discloses a biaxially oriented film containing polyethylene-2,6-naphthalenedicarboxylate as a main component, the film being a polyester film for use in a TAB leader tape, having a film thickness of 75 μm or more. It is further disclosed that instead of employing an extremely expensive film having high heat resistance, the use of this polyester film also imparts heat resistance to an extent durable for practical use to the lead tape; necessary performances other than heat resistance are not addressed although attention is directed toward the high cost of a super engineering plastic.
However, as a result of studies by the present inventors, it has been found that a TAB leader tape comprising a super engineering plastic is highly water-absorbing and has a limitation to the frequency of recycling. It has been also shown that when guide holes for meshing with a roll are punched out in opposite sides of a tape material for a TAB leader tape, as burrs, elongated whisker-like pieces project from the tape and powder is generated. The elongated whisker-like pieces generated as burrs are particularly problematic because they can be injurious to semiconductor devices. A TAB leader tape comprising polyethylene-2,6-naphthalenedicarboxylate also has problems, e.g., that it is highly water-absorbing, generates burrs when punched out, and is large in dimension change due to water absorption and temperature dependency of elastic modulus.
Thus, an object of the present invention is to provide a TAB leader tape excellent in resistance to water absorption.